Method of preparing synthesis gas at elevated pressures



Dec, 8, 1953 P. GAUCHER METHOD OF PREPARING SYNTHESIS GAS AT ELEVATED PRESSURES 2 Sheets-Sheet 1 Filed Oct. 1, 1948 .R m M mm w 3 A T a T .A mg N M v. :w qi B Q S M Dec. 8, 1953 P. GAUCHER METHOD OF PREPARING SYNTHESIS GAS AT ELEVATED PRESSURES 2 sheets-sheet 2 Filed 001;. l, 1948 W A'Z'TORN Y Patented Dec. 8, 1953 METHOD OF PREPARING SYN-THESIS GAS. AT ELEVATED PRESSURES I Leon P. Gaucher, Tuckahoe, N. Y., assigiuorv to.

The Texas Company, Ne

ra on. f D l re Application October 1, 19.48,: Serial .No..52-,32.4.

ac ns- (arise-1.9a).

This invent on r lates aefie ne endo herm conve i ns. s ou rea a t 1 t elevate emp rature. and pressure- M re. par icularl the inven ion; on ernsv rep r th is re comprising carbon onoxide and hydro en. l an ele tedpress re bizh acti cf a hydr carbon as. suchas. methane th t am oarhon-diox d The sent application a-coht nuat nr npart; f; y; appendin app ica ion S al: No 5771: 371, fil d; u e. .1,. 5i6, ow a andoned,

he c rry-i s ut endoth mic conv rsions o-ieaseous. reactants attemp ratures ab ve. abou 1.2.9.0.? FL ndat pressures. above .ahoutlao 1 2 5.net ouareinc eauaeishesetwith oper tinsd ucuk ties. Heat must be supplied to fuliilhthethermw .dsznam c requirements-oi the. rea t n an .att ame. me h -j. pre sure. mu t; e maintained t the: de red; l yehw It. the. ves e is con tru ed so that it can withstand an; elevatedpressure, he t s. difiicultto. supply th required. h a aiueo r he bulky ons ructionof :apressurized vessel. When the construction of .a reactionvessel is such that heat may be readily. supplied thereto, the vesselordinarily will not withstand elevate rressures. The method; of; this inveni n presents a imple. answer to h pr l ms inherent, in such operation and: obviates the difrioulties attendant upon-performing endothermic lfeactionaat elevated temperatures and pressures. accord- .with themethod of this invention, acarbonaceous material is completely oxidized in .a combustion. or exothermic zone in. a furnace und r elevated temperature and pressure. Disposed in. indirect heat. transfer relationship with th s. hi hpressure combustionzone, is an endothermic;reaction-.zone to which the high pressure heat of combustion is continuously transferred to thermally supportthe segregated endothermic reaction going on therein. The endothermic zone, for. examplamaybe confined: or segregated yvithina. tube, aplurality-of tubesora tubular v.coili. preferably arranged int'erspatially "of the combustion zone; so. that the confining surfaces of: the... endothermic zone continually transmit thermaLenerey to; the interior.

teriorly. through the endothermic, zone,- as for .fiiem e thro h ubes. ducts Q1; passageways therei In any event, he. e qt'lleltmifi'; zone. is

Alternatively, the. pressure: cornbustionzone may. extend. in-

.ee sg i i indirec heat v hansfier.-.relati mship lw'it'hhthe pressu combustionzone .by virtue o an intervening. mpermeab e. heat transferharr1 1...

are introduced into the endothermic zone. atan elevated pres'surewhich is substantiallyequivalent to thatmaintained in the combustion zone during oxidation of a carbonaceous. material therein. Gaseous reactants are converted e; sired products at elevated temperatureland sure during their passage through. the endothermic zone which maybe occupiedby 'aQcatalystmaterial. The heat required for the do;- thermic conversion is supplied bythecomb st n taking place under press re withinfthe tion zone.

h car onac o sma ria ic i eoinnletely oxidized in the combustionlzoh e' o f't h' -f may consist of natural gas other. gaseo liquid fuels of any type, or. a migturelof; gaseous andliquid fuels.- W

scli u ls. su h s coa r c e ma -e ect e r ed h rere ire cq us ion zone; a o exam l y. in e i t e n w er r. ticleforrn ina stream of qxidizinggas.

h lim te ihis. nven on s; most. us iu e r e mine end hermic reac ons at sures b ve qutli b uers ua e melee. eda em er r s abo e about 2 97-3. Ma end th rm c rea tion suc as' t e r Y methane with carbon dioxideor-stea I hemai en nce o atemp ra u a eye tia lv i v xc s o .2. 0? a forexamp ei the rangeo to 29. 191 I imrderitq ef c rea ti n- Wh n 911941 1? or. o e g. considera on dic ate, tha usi;- areaai. me a a l v dp ssu ei his x y ut e pro de a r t a metho f f ect n suc reaction. A

Th es u urnace. which he c rbon ceous-mat ia s. osidia dto u lyheat anib Qiulk nstr et on with he 2 1.

walls. The Walls may be lined with a sulating layer of refractory material. Insulation of the furnace with layers of refractory material prevents the outer wallafrom overheating. .By constructing. the furnace so that there isino substantial pressure differential through the combustion zone, objectionable-leakage"of gas through the refractory material is avoided, the development o'f-hot spotsin the furnace wall thus. bein r vente A wide choice of heat-resistant alloys, are

eva l bl fro wh c he hea tran e b rier,

su a h ub or t be fil fiiw il m th re e r camw b nst uc ed.-. hi -aesure. on e e si e o the ube wall Q barii eri substant ll h some; and there a her -.1

l sst iaa9t i i i s eefi the ui c reactio sc necessit fo .heavr wa l constructi n.- 'Trhe only limitation put upon the structure of such heat transfer surfaces is that they be made of a material which is able to withstand oxidation or reduction at elevated temperatures. Alloys such as the chrome steels are representative of the type of material from which such surfaces or barriers may be constructed.

The endothermic zone may be packed with catalyst in order to increase the rate at which the endothermic reaction occurring therein takes place. The choice of catalyst will depend upon the particular endothermic reaction. Thus, for example, a nickel on alumina catalyst may be used to pacl: the tube for the reaction between methane and carbon dioxide to produce a mixture of carbon monoxide and hydrogen.

Advantageously, however, from the standpoint of conversion efficiency, the catalyst occupies the endothermic zone as a fluid phase of solid particles.

Thus, it has been discovered that the dense fluid catalyst mass extraordinarily increases the rate of heat transfer to the endothermic zone. Presumably, this follows from the fact that the rapidly vibrating particles of the fluid phase function as heat transfer bodies capable of overcoming the insulatory gas film effect which characterizes heat flow between fluids and heating surfaces. In any event, however, the desired thermal flow into the endothermic zone is remarkably increased, and the contact mass moreover assumes a highly desirable uniformity of temperature which may be controlled at any predetermined reaction temperature by regulating the rate of reactant feed, or the like.

Maintenance of the particles in fluid phase condition may be effected by upflow of the reactants at a suitable linear velocity, or alternatively by subjecting the particles to mechanical aeration, as by an agitator or rotating impeller. Conditions suitable for a dense fluid phase are advantageous in that they permit continuous separation of the product gases from the upper pseudo-liquid level of the contact mass.

The process of this invention is particularly well adapted to the preparation of synthesis gas comprising carbon monoxide and hydrogen by the reaction of a hydrocarbon gas such as methane with carbon dioxide or steam or a mixture of the two; such synthesis gas may then be converted into hydrocarbons, oxygenated hydrocarbons and the like by procedures which are well known in the art. The preparation of synthesis gas by the reaction of a hydrocarbon gas such as methane with carbon dioxide or steam or a mixture of the two is a highly endothermic reaction. The reaction of methane with carbon dioxide in accordance with the following equation,

is endothermic to the extent of 2140 B. t. u. per pound of methane at 2241" F. The reaction between methane and steam according to the following equation,

is endothermic to the extent of 1885 B. t. u. per pound of methane at 2241 F.

Both of these reactions require that the temperature level be maintained at or above about 1500 F. in order for the reactions to proceed at an economically feasible rate even if a catalyst is used. Moreover, when the hydrogenation of carbon monoxide in a subsequent step is to be performed at an elevated pressure, considerable economies in compression cost are realized if the preparation of synthesis gas is conducted at elevated pressures. The reason for this lies in the fact that the preparation of synthesis gas by either of the above two equations results in a twofold volume increase which may be readily ascertained from an inspection of the equations aforementioned. Thus, if the reactants rather than the products are compressed, as is the situation when the endothermic conversion is performed at elevated pressures, approximately a 50 per cent saving in compression cost may be realized.

Moreover, by the present invention, the flue gas discharged from the combustion zone at elevated temperature and pressure is utilized to generate power for compression of the feed gases as well as to generate steam for use in the endothermic conversion.

In order that the invention may be more fully described, reference will now be made to the Figure 1 of the accompanying drawing, in which the use of the invention for the preparation of synthesis gas is illustrated.

Fuel gas, such as natural gas, and air obtained from sources not shown, are passed through pipes l and 2 respectively-to compressors 3 and 4 respectively wherein they are compressed to an elevated pressure of about 250 pounds per square inch gauge. The compressed gases then flow through pipes 5 and 6 to the combustion side of a furnace I wherein combustion is effected under about 250 lbs. per square inch gauge and at a temperature within the range of about 1800 to 3600" F.

Oxygen or gas rich in free oxygen may be used instead of air, but an advantage of the process is that air can be used without adding nitrogen to the synthesis gas.

The pressure furnace I is constructed to withstand high pressure and temperature levels. It comprises a metal vessel lined with refractory material. It is preferred that the combustion zone be sufiiciently unobstructed so that there is substantially no pressure differential between the feed gas inlet and the flue gas outlet.

Within the pressure furnace 1, there is positioned tubing 8 made of high temperature resistant alloy. This tubing is advantageously constructed in the form of a coil so to minimize structural stress resulting from the differences in the coefficients of expansion of the high temperature resistant tubing and the material of which the pressurized furnace is constructed. This coil is in fluid communication with the exterior of the pressure furnace so that gaseous constituents which react endothermically may be introduced to the coil and discharged therefrom to the exterior of the pressure furnace.

An eflluent combustion gas comprising nitrogen, excess oxygen and the products of combustion, namely carbon dioxide and steam, leaves the pressure furnace I through a pipe 9 at a pressure of about 250 pounds per square inch gauge. This gas is passed into an exchanger ill wherein its temperature is lowered from about 2500 F. to about 1000 to 1500 F., giving up its heat to water and thereby generating steam. The steam generated in the exchanger I0 discharges therefrom through a pipe l2 and is used in the methane-carbon dioxide-steam reaction taking place within the coil 8.

The partially cooled gas stream leaves the exchanger ll] through a pipe II which leads to a densed' Water "and 'gases' such as carbon dioxide, f

nitrogen and oxygen,"passes 'through' apipe into a'gas liquid separator 2|. Water issepa- "rated from the "gaseous constituents "and "dis- 'chargedfrom the separatori I through a'pipe-ZZ. fThe gases whichhave been separated from the condensed water leavethe'separator 2 I through a iipipe23"and'are introduced'into a'scrubber'24 of f'a. carbon 'dioxide'absorption unit. In the" scrubber "24,the 'i gases flow countercurrently to an alkaline solution such as an aqueous solution of 20 mono'ethanolamine 'whereby the carbondioxide present in the gas stream is separated therefrom by"-absorption in the liquid. Unabsorbed'gases :comprising mainly nitrogen leave the scrubber through. I

*Monoethanolaniine solution saturated with =carbondioxide continuously leaves the scrubber 24 through'a pipe 25 and is introduced into a -stripper '21. 'In the stripper 2'1, monoethanol- =actants which undergo endothermic conversion 40 -in the tubing 8.

Compressor I5,-previously referred to, serves to raise the carbon dioxide to the pressure at *which'the endothermic conversion takes place. The carbon dioxide recovery may be carried out "under-substantially the-same pressure as prevails atthe outlet of the turbine, 'for example, 'about' 50 pounds gauge.

Methane, or a gas containing 85 to-95per cent methane, is obtained from a source not shown 'through-a'pipe38 and isadvantageously passed to'the compressor is wherein itand the aforesaid carbon dioxide are raised to 250 lbs; pressure. i-ENatural 'gas may be available at sufiiciently high gpressure so that it requires no further compresision.

Steam at approximately the same pressure, ."namely about 250 pounds per-square inch gauge, zis obtained at least in part from the exchanger Ill! through the pipe l2 and combines with meth- -1ane in the discharge conduit 39 from the comipressor l5.

Additional steam-and carbon dioxide, if required, can be drawn from outside sources not :shown in the drawing. i

Methane, 'steam'an'd'carbon dioxide arecomebinedzin theiconduitfia prior to their introduc- :%tion into the tubular endothermic reaction zone 8. The mol ratio of these reactants depends zupon reaction temperature, type of catalyst, if 'any,=and upon what molecular ratio of carbon -'?monoxide to hydrogen is desired in the resulting 'zsynthesisgas. A reactant mixture containing a tmole'cular' ratio ofttwo mols of methane .tolone each of carbon dioxide and steam gives a synthesisgas'containin'gmydrogen=and-carben moii oi'tid'efin the molecular ratio of 221 at lSOO F. "in the'fpresence of *nickel catalyst. A' reactant mixture idf-ene-"mol of "methane to "one mol pf '5 steam-gives a'synthesis'gas comprising hydrogen and; carbon monoxide *the approximate ratio of 331. 1Areactantmixturecontaining 'n'iethane r and-carbon dioxide in the mol-ratio of 1 :1 mitler 'sirnilar'con'ditions yi'el ds *syntheSis gas containing hydrogen "andcarbon "monoxide :in the approximate ratio of 1:1. These relationships may T be seen from "the following *equations:

. w(3H444302:ZC'OF2H2 -:It:is apparentsthat the makeup ofzthetmesultin s synthesis gaalm'ay be varied Withinfthe approxiimate .cmol ratio atlimits :zof hydrogen to acarbon mnonoitideaofsl'z l i033 :'1;:by waryingitheszmakeup wrpfYtheJreaCtants The reactant mixture eisiintroducediinto zthe lzcoil 8s'f-rom therlcon'duitsfl. The :c0i1'i8 may be duithrough a pipe 25 and are Vented there "filled withvinickelifdeposited onsaluminacwhich :cat'alyzes therrea'ction of methane s-with-xcarbon adioxidezan'd :steam. :On :passa'ge :throughnthe ".COilli-Bfi the: reactants: areiizaised to iaitemperature .:level: excess :of 1600:F.ithrough2the:heats-sup- O zplied doy the ::pressure combustion -taking "-place on theaexterior.:of'itheicoiliz8. izThetrreactants rare z'converted into :carbon amonoxide: and hydrogen 'i-idurting passageithrough the coil.

thaispray of water fromarpipe dl :may bei'intro- .adueed'rintocthe hot-'lproducts of the endothermic :reaction:as-theyxleavertheitube 8. The purpose rofethe Water: spray. is to serveias aquench. 'I he .L'IJI OdUCtSLDfLCOHVBlSiOIl zpro'ceed along a pipe 242 at a reduced temperaturerinto a-rcondenser xin;.which=:the;;steam present in the'product is ccond'ensefd. 'iTheifluidz-ipro'duct then 'flows along -aa:,pipe 451:into azgas-rliquid separator fli in which econdensed water: :is separated from the gaseous :constituents. lWater is discharge'd from the sep- :aarator 46;throughaa lpipe l'l. 1 I 'IEheunormalllygaseousconstituents from-which @watervhasnbeen separated-leave the 'separ'ator 'fli athrorughzazpipe: 48. 'Ihis gas comprises mainly A carbonvmonoxide Land 3 hydrogen in the desired molecular ratio which is ordinarily =abo1'it 1':'2. 50 zT-his {synthesis gas I is lat "anaelevated -pressure r randuis :advantageously :used directly i-n -tha' proraduction :'1of;;;liquid ;rhydrocarbons '-='in "the gasoline range by;contact with a z'c'atalyst containing a :metalcof theeighthfgroumsuoh as iron. :Thersynthesis. gas'aataan elevated"pressure pro- :ceed-szi'along thegpipe-M-B 2 and is 1 introduced into --.a-='synthesis. reactor-r19. In the reactor- 49,'-synethesis; gasiris converted atmanelevated pressure allltOyPI'OdLlCtS. comprising main'ly' liquid hydro- 6o -;carbons lin=;, the =;gasoline: .ran'ge. The-products of leactiondssue fromzzthe reactor' w through a -pipe 2 50 andzare: thereafter introducedinto a *=separratingztand'zfractionating systemfnot shown.

:m fluidnbed-type of-reactor operated at about 250 pounds per square inch gauge pressurefat about 600 and using an unsupported "iron catalyst is effective in'preparing liquidi'hydrocarbons in the gasoline range. The composition of unsupported iron catalystused under these conditions. is approximately as followszi93 t0-95 percentmet'alllic iron, 3 00.6 percent-alumina and 0.2 .toe2 per cent alkali'metal oxide,;;-such i as potassium oxide.

v Figure 2 of the drawing presents a somewhat modified embodiment of the invention employing a fluid phase contact mass in the endothermic zone. Therein a fuel such as a natural gas or powdered coal is passed through pipe 55 simultaneously with the passage of an oxidizing gas such as air through compressor 56 and pipe 51, to a combustion zone 58 of a furnace 59. As before, the combustion zone is preferably maintained at a high pressure, for example, 250 p. s. i. g., and a temperature within the range from about 1800 to 3600 F.

Combustion is initiated within the upper enlarged cylindrical portion of the furnace 59 and completed within the vertical tubes 60, the burning reactants flowing downwardly therethrough and yielding a flue gas in the lower portion SI of the furnace. In the present embodiment, the endothermic reaction zone surrounds the combustion tubes 68 within a vertical cylindrical chamber 63. More specifically, the endothermic reaction zone is situated intermediate of upper and lower tube plates 55 and 66 respectively, in the space about tubes 69.

Just above the lower tube plate 66, the tubes extend through a distributing plate 61, preferably formed of some porous refractory material such as sintered silica, alumina or the like. The

distributing plate 67 may be alternatively a perforated or reticulated metal. The plates 66 and B1 accordingly define between them a header for I the incoming reactants introduced through side arm 68. As said before, the reactant hydrocarbon may comprise preheated methane flowing through the side arm 68 from any convenient source not shown, through inlet pipe 10 and heat exchanger 1!. Water injected through pipe 12 into waste heat boiler 13 supplies steam through pipe 14 and preheater 15 into admixture with the methane in the header.

The reactant mixture at reaction temperature passes upwardly through the distributing plate 6? through a dense fluid phase of solid particle catalyst surrounding the combustion tube 60 and indicated by the reference numeral 15. It is to be understood that the linear upfiow velocity of the reactant is adjusted with due regard to the settling rate of the catalyst par ticles such that the uniform dense phase rises to a pseudo-liquid level represented by the numeral 18.

In the disengaging space between the upper level 18 of the contact mass and the upper tube plate 65, the effluent product stream is collected and flows outwardly through side arm 79 to a separator such as the cyclone 80. Obviously, any magnetic or electrostatic or any other convenient form of separator may be substituted at this point to remove any inevitable small amount of entrained catalyst particles which are discharged through standpipe 8|. The product gases comprising essentially hydrogen and carbon monoxide, at a temperature of, for example, 2000 to 2500" F., flow through pipe 83 to waste heat boiler 13, from which they are discharged for subsequent utilization as in the previous em- 1 bodiment.

all)

to the contact particles. Since the rate at which the reaction can be effected is normally limited by the transfer of heat energy into the endothermic reaction zone, the present arrangement substantially multiplies the capacity of the endothermic reaction zone and makes possible the conversion of phenomenally larger quantities of reactants than is possible Where the contact mass is packed or otherwise disposed in the reaction zone to form a fixed bed. The phenomenal improvement in heat transfer following from the provision of the fluid phase of particles is, however, present, irrespective of whether the particles are catalytic or inert, and accordingly, a noncatalytic fluid phase is contemplated under reaction conditions where a catalyst is not requisite.

For the purpose of permitting the regulation of peak combustion temperatures to prevent undesirable overheating within the combustion zone, provision is made for recycling a portion of the product flue gas. To this end, the flue gas collecting in the lower chamber 5: of the furnace passes through pipe 88 and after passing through preheating exchangers l5 and ll as indicated, moves through conduit to branch line 86, leading to the inlet of the combustion chamber where it mixes with the fuel and oxygen streams of pipes 55 and 51 in the initial combustion chamber 58. The flue gas over and above that required for temperature control continues into expansion engine 81, furnishing the energy to drive compressor 56. The final flue gas is vented at an appropriate lower temperature through pipe 88.

Obviously, from the foregoing, the expansion engine may operate to supply mechanical energy as needed to compress other streams, as for example, the fuel supplied to the combustion zone where gaseous fuel is employed.

In place of the water vapor stream of inlet pipe "i l, carbon dioxide, as indicated above, may be substituted in whole or in part.

In view of the critical requirement that the endothermic reaction zone be maintained continuously under a pressure substantially the same as that prevailing in the high pressure combustion zone, it is understood that in practical operation, suitable instrumentalities will be provided to maintain this condition. In view, however, of the variety of forms of equipment and the conventional principles involved, it is evident that the details thereof are neither appropriate or necessary.

In the description of the invention, natural gas has been mentioned as the fuel gas burned in the exothermic zone. However, other carbonaceous materials, such as fuel oil, shale oil, etc, may be used.

Obviously, many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof and, therefore, only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. A process for continuously generating carbon monoxide and hydrogen which comprises passing a stream of a hydrocarbon gas and a reactant selected from the group consisting of steam, carbon dioxide and a mixture thereof into a reaction zone maintained at a temperature above 1,200 F. and a pressure above about pounds per square inch gauge into contact with a bed of solid contact material in particle form maintained in dense fluid phase condition by the flow of reactants therethrough, effecting reaction between said hydrocarbon and said reactant within said reaction zone to form carbon monoxide and hydrogen, subjecting carbonaceous material to combustion in a separate combustion zone maintained at a temperature in the range of 1,800 to 3,600 F. and a pressure substantially equivalent to the pressure in said reaction zone and passing the resulting combustion gases maintained under said elevated pressure through said fluidized bed of solid contact material in indirect heat exchange therewith to supply heat to said reaction zone.

2. In a process for generating carbon monoxide and hydrogen from a plurality of reactants consisting of a hydrocarbon gas and a reactant se lected from the group consisting of steam, carbon dioxide and a mixture thereof, the improvement comprising introducing said reactants into the lowermost portion of a reaction zone within a pressure vessel, maintaining a dense phase fluidized bed of solid contact material within said reaction zone, said bed occupying the lower portion of the reaction zone and having an upper surface below the uppermost portion of said reaction zone, introducing said reactants at a rate sufficient to maintain dense phase fiuidization of said contact material, maintaining a pressure above about 150 pounds per square inch gauge and a temperature above 1200" F. in said reaction zone, subjecting carbonaceous fuel to combustion in a separate combustion zone within said pressure vessel maintained at a pressure substantially equivalent to the pressure in said reaction zone, and passing the resulting combustion gases while under said pressure into said fluidized bed of solid contact material in indirect heat exchange therewith, thereby supplying heat to said reaction zone.

LEON P. GAUCHER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,903,845 Wilcox Apr. 18, 1933 1,959,151 Beekley May 15, 1934 2,389,636 Ramseyer Nov. 27, 1945 2,399,450 Ramseyer Apr. 30, 1946 2,425,754 Murphree et a1. Aug. 19, 1947 2,478,912 Garbo Aug. 16, 1949 2,547,135 Mercier Apr. 3, 1951 FOREIGN PATENTS Number Country Date 310,686 Great Britain May 2, 1929 604,373 Great Britain July 2, 1948 

1. A PROCESS FOR CONTINUOUSLY GENERATING CARBON MONOXIDE AND HYDROGEN WHICH COMPRISES PASSING A STREAM OF A HYDROCARBON GAS AND A REACTANT SELECTED FROM THE GROUP CONSISTING OF STEAM, CARBON DIOXIDE AND A MIXTURE THEREOF INTO A REACTION ZONE MAINTAINED AT A TEMPERATURE ABOVE 1,200* F. AND A PRESSURE ABOVE ABOUT 150 POUNDS PER SQUARE INCH GAUGE INTO CONTACT WITH A BED OF SOLID CONTACT MATERIAL IN PARTICLE FORM MAINTAINED IN DENSE FLUID PHASE CONDITION BY THE FLOW OF REACTANTS THERETHROUGH, EFFECTING REACTION BETWEEN SAID HYDROCARBON AND SAID REACTANT WITHIN SAID REACTION ZONE TO FORM CARBON MONOXIDE AND HYDROGEN, SUBJECTING CARBONACEOUS MATERIAL TO COMBUSTION IN A SEPARATE COMBUSTION ZONE MAINTAINED AT A TEMPERATURE IN THE RANGE OF 1,800 TO 3,600* F. AND A PRESSURE SUBSTANTIALLY EQUIVALENT TO THE PRESSURE IN SAID REACTION ZONE AND PASSING THE RESULTING COMBUSTION GASES MAINTAINED UNDER SAID ELEVATED PRESSURE THROUGH AID FLUIDIZED BED OF SOLID CONTACT MATERIAL IN INDIRECT HEAT EXCHANGE THEREWITH TO SUPPLY HEAT TO SAID REACTION ZONE. 